The rap on solar is that it can't scale up fast enough to make much difference in solving our nation's energy challenges. BrightSource aims to help change that with its $2.1 billion, 392-megawatt solar thermal plant in the Mojave Desert that will generate enough electricity to power 140,000 homes; the Ivanpah facility will go online in 2013. The technology is different from photovoltaic panels, which are also used in big utility projects. The BrightSource plant employs 350,000 mirrors that rotate to track the movement of the sun and reflect its heat onto a 450-foot tower. The sun's heat boils a tank of water in the tower, which creates steam, which runs a turbine that generates electricity. Jay Holman, a research manager at consulting firm IDC Energy Insights, says the electricity this plant generates will be more expensive than that from coal- or gas-fired electric plants. The company believes it can get its prices competitive by mid-decade.